1. Field
The present disclosure relates to an adaptive pinhole single photon emission computed tomography (SPECT or SPET) which provides superior spatial resolution and detection efficiency trade-off as compared to a conventional parallel-hole collimator for imaging small field-of-view (FOV).
2. Background
Single photon emission computed tomography (SPECT) is a nuclear medicine tomographic imaging technique using gamma rays. Previously an adaptive multi-pinhole (MPH) collimator for clinical myocardial perfusion imaging (MPI) and small animal imaging (SAI) of rats was developed. The MPH collimator was based on a dual-head clinical SPECT/CT system, as described in G. S. P. Mok, B. M. W. Tsui, Y. X. Wang, F. P. T. Choi, G. Yip and A. Ahuja, “Design of a multi-pinhole collimator for high performance clinical and preclinical molecular imaging,” J Nucl Med., vol. 51, p. 1393, 2010.
The design of MPH collimator depends on specific detection efficiency and resolution requirements for different imaging applications. In order to determine the optimal MPH collimator design, P. Nillius and M. Danielsson, “Theoretical Bounds and System Design for Multipinhole SPECT,” IEEE Trans. Med. Imag., vol. 29, pp. 1390-1400, July 2010, proposed an analytical model and showed that the image quality in terms of resolution and detection efficiency are related to several parameters: the diameter of FOV (d), radii-of-rotation (l), collimator length (L−l), detector intrinsic resolution (Ri) and the size of the active detector area (A). Those MPH collimator configuration parameters can be determined for a given system resolution (Rt) and FOV (d) in order to optimize the detection efficiency (S). On the other hand, M. C. M. Rentmeester, van der Have, F., Beekman, F. J., “Optimizing multi-pinhole SPECT geometries using an analytical model,” Phys Med Biol, vol. 52, pp. 2567-2581, May 7, 2007, developed a continuous analytical model for optimizing the MPH SPECT geometries and they suggested that the pinhole apertures should be placed as close as possible to the object, i.e., minimizing the imaging distance, in order to optimize the resolution-detection efficiency trade-off.